Explosion gas turbine plant



Nov, 11, 11952 J. H. ANDERSON 2,617,254

EXPLOSION GAS TURBINE PLANT Filed Jan. 29, 1948 HIS ATTORNEY.

Patented Nov. 11, 1952 SAT NEFE

PENT OFFICE EXPLOSION GAS TURBINE PLANT Application January 29, 1948,Serial No. 5,097

4 Claims.

This invention relates to gas turbine plants, and more particularly to aresonant explosion unit for generating explosion gases to operate aturbine.

One object of the invention is to produce a maximum volume ofturbine-operating gases with a minimum quantity of fuel by combining theexplosion gases and separate volumes of air compressed by the pressurewaves of the explosions.

Another object of the invention is to utilize pressure waves from theexplosions in the explosion unit for compressing a supply of air whichis in turn heated and then introduced into the explosion gases to coolsaid gases suitably for use in a turbine.

Another object is to utilize the gases discharged from the turbine forheating the air compressed in the explosion chamber.

A further object is to introduce a spray of water into the cooling airso that good heat transfer is obtained between the turbine dischargegases and said cooling air.

Other objects will be in part obvious and in part pointed outhereinafter.

In the accompanying drawing in which similar reference numerals refer tosimilar parts,

The figure is a side elevation, partly broken away, of a gas turbineplant constructed in accordance with the practice of the invention andshowing the position of the controlling devices when at rest.

Referring more particularly to the drawing, a resonant explosion gasturbine plane, designated in general by 20, is shown as including aturbine 2|, a resonant explosion power unit 22 for providing theoperating gases for the turbine, and a compressor 23 driven by theturbine for delivering compressed air to the power unit '22.

The compressor and the turbine are of the axial flow types having theirrotors 24 and 25 coaxially arranged with each other and the opposed endsof their shafts 26 and 21 connected together by a coupling 28. On theother end of the shaft 21 is a power take-off coupling 29, and the outerend of the shaft 26 carries a clutch member 30 for engagement with amating member on a shaft 32. For starting purposes, a motor 3| isadapted to impart rotary movement to the shaft 32 through a belt drive33 causing the initial rotation of the rotors 23 and 25. The clutch isoperated by a lever 34 attached to one of the clutch members and pivotedon a stationary member I9.

The resonant explosion power unit 22 in this case comprises a casing 35which forms an explosion chamber 36 having an explosion zone 3] and acompression zone 38, and a heat exchanger 39 for heating the compressedair discharged from the compression zone 38.

The air discharged from the compressor 23 is conveyed to the explosionzone 31 and the compression zone 38 by a conduit 40 which leads to ports4| and 42 in the casing 35 located respectively adjacent the zones 3'!and 38. The flow of air through the ports 4| and 42 is controlled bypressure responsive valves 43 and 44, respectively. Both valves areshown as being of the poppet type and are normally held unseated bysprings 45.

Fuel is injected into each charge of air entering the explosion zone 31through the port 4| by a spray nozzle 46 in the casing adjacent theexplosion zone, and the explosive mixtures thus formed are ignited by aspark plug 41 projecting into the casing in the transverse plane of thespray nozzle. The fuel is conveyed by a conduit 38 to the spray nozzle43 from a fuel pump 49 which may itself receive fuel under pressure froman outside source (not shown). The piston 50 of the pump 49 is actuatedby a rocker arm 5| operatively connected to the shaft of a motor 52, ina well known manner, for pumping fuel to the nozzle 46. An interrupterdevice 53 in an ignition circuit 54 for the spark plug 41 is alsoactuated by the rocker arm 5| to produce a spark in timed relation withthe operation of the fuel pump 49.

The casing 35 comprises two cup-shaped members 55 and 56 having theirinner open ends spaced with respect to each other to providetherebetween an exhaust opening 51 for the exhaust gases from theexplosions in the explosion zone 37. Surrounding this opening andattached to the casing is a housing ring 58 for conveying the explosiongases to an exhaust conduit 59 leading to the inlet of the turbine 2|.

In order to discharge the air from the compression zone 38 of theexplosion chamber, a port 60 is provided in the casing at a pointadjacent the compression zone, in this instance it is shown as being inthe transverse plane of the port 22. A check valve 6|, normally heldseated in the port 6|! by a spring 82, controls the flow of compressedair passing through the port 60 into a discharge conduit 63.

The compressed air from the compression zone 38 is conveyed, by theconduit 63, to the heat exchanger 39 which is provided with a tube nest34 over which the air passes. An air conduit conveys the air from theheat exchanger to the exhaust conduit 59. The heating medium for theheat exchanger 39, in this case, consists of the gases discharged fromthe turbine 2| which 3 are conveyed to the exchanger 39 by a conduit 66.The discharge gases from the turbine pass through the tubes of the tubenest 64 and are discharged to the atmosphere through a pipe 87.

In order to cool the compressed air and to increase its mass flow beforeit enters the heat exchanger 39, a spray nozzle 68 is provided in thedischarge conduit 63 and connected to a water supply (not shown) forintermittently or constantly spraying water into the air passing throughthe conduit 63. Since the mass flow of the turbine discharge gases isgreater than the mass flow of the air discharged from the compressionzone 38, the addition of water to the air raises its mass flow such thatit will absorb a great amount of the heat contained in the turbinedischarge gases passing through the exchanger 39. It will be readilyunderstood, however, that a spray of water could be introduced into theair during its passage through the conduit 40 with correspondingdesirable results.

The length of the chamber 36 is so chosen and the frequency of theexplosions in the chamber is so timed that when a pressure wave from anexplosion is at its peak in one end of the chamber it willsimultaneously be at its lowest value in the other end of the chamberand to this end the length of the chamber 36 approximates one half of apressure Wave length or an odd multiple thereof. In other words, whenthe aforesaid pressure condition exists within the chamber 36, thefrequency of explosions in the explosion zone 31 will be equal to, or afunction of the natural frequency of the chamber 36,. It is apparentthen, from the foregoing discussion, that in order to obtain the properfrequency of explosions such that the explosions occur at a time whenthe peak of the reflected pressure wave exists in the explosion zone 31,it is merely necessary to vary the frequency of the explosions-bycontrolling the speed of the motor 52 in any well-known manner, such asby varying the voltage impressed thereonuntil the aforesaid condition isobtained. As a guide for regulating the speed of the motor 52 thepressures at various points in the explosion chamber may be measured byany well known device (not shown).

For any given condition-that is, length of the chamber 36 andtemperature and pressure of the gas within the chamber 36, there is afixed frequency, or direct function of this frequency at which the powerunit will operate most effectively. Under these given conditions thelength of a pressure wave in the chamber 36 is determined by the lengthof time it takes for the peak of the wave to travel from the explosionzone 31 to the compression zone 38 and return to its point of origin.This time is, of course, dependent on the distance travelled (twice thelength of the chamber 36) and the speed at which the wave travels(depending on the temperature and pressure within the chamber 36).Inasmuch as the pressure and temperature within the chamber 36 isdependent, in part, on the mixture and type of fuel used and the size ofthe chamber 36, a practical method for obtaining the proper timingrelation is facilitated by the expedient of measuring the pressure atthe explosion end of the chamber 36 and igniting. the explosion mixtureduring a period of maximum pressure at that endby maximum pressure it,is meant, of course, the maximum pressure at that end of the chamberprior to the explosion, or in other words, the maximum pressure causedby the refiected pressure wave, which maximum pressure would occur whenthe peak of the reflected pressure wave reached the explosion zone 31.An alternative method would be to measure the pressure at the exhaustopening 51 and varying the frequency of explosions until a relativelyconstant pressure is obtained at this point. An end plate 69 of thecasing serves as a reflecting member to reverse the direction ofmovement of the peak of the pressure waves in the chamber 36 on contacttherewith.

At the beginning of an operating period of the plant, the starting motor3| imparts rotary movement to the rotors 24 and 25 causing compressedair to flow through the conduit 40. Part of this air will pass throughthe port 4| into the explosion zone 31 while the remainder will passthrough the port 42 into the compression zone 38. If then the fuel pumpmotor 52 is put into operation, fuel will be injected into the charge ofair in the explosion zone 31, and the resulting explosive mixture willbe ignited by the spark plug 41. This initial explosion forces the valve43 to its seat, thereby cutting off further flow of air through the port4|. The peak of the pressure wave from the explosion travels toward thecompression zone 38 causing a low pressure area to exist therein whichpermits the valve 43 to open and admit a new charge of air into. theexplosion zone. As the peak of the wave reaches the compression zone 38,it causes the valve 44 to seat, cutting off the flow of air through theport 42, and further compresses the charge of air in the compressionzone 38 to such a pressure that the valve 6| is forced open to allow thecompressed air to pass into the discharge conduit 63.

When the peak of the pressure wave hits the end plate 69, it isreflected thereby and will return back to its point of origin, thuspermitting the valve 6| to be returned to its seat by the spring 62 andthe valve 44 to open to admit a new charge of air into the compressionzone 38. The peak of the reflected pressure wave moving toward theexplosion zone 31 compresses a new charge of air therein, and at theinstant of peak compression, fuel is injected through the nozzle 46 intothe compressed air and this mixture is ignited by the spark plug 41Thus, another wave is started which continues through the same cycle asthat just described.

It is to be noted that due to the location of the valves 44 and 6.! and.the manner in which they are operated, the air passing from thecompression zone 38. through, the discharge conduit 63 is substantiallyfree of any of the products of combustion from the explosion zone 31.The reason for this is that the valve 44 isheld in the open position bythe spring 45 except during a relatively short period in the explosioncycle when the peak of an explosion waye approaches the explosion zone38- and is reflected therefrom,-

whereas the valve BI is held closed except during the aforesaidrelatively short period of an explosion cycle during which time thevalve, 44 is closed. Thus, a greater amount of air passes into thecompression zone 38 from the conduit 40 than passesfrom this zonethrough the conduit63.

The excess of air valvedinto the compression zone 38 moves along the;explosion chamber 36 toward the exhaust conduit 59 thereby opposing anycounter fiow of exhaust, or combustion, gas from the explosion zone 31,thereby effectively preventing the mixing of combustion gas with the airdischarged through the conduit 63. The air moving; from the compressionzone 38 mixes with the combustion gas at the exhaust conduit 59 therebyserving not only to increase the quantity of gas discharged at arelatively constant pressure through the conduit 59, but also to reducethe temperature of the fluid heated in the explosion zone 31 to a valueat which the resulting mixture may be safely utilized in driving theturbine 2 I. In the form of the invention wherein the air valved fromthe compression zone 38 is subsequently mixed with the aforesaid mixturebefore use in the turbine for purposes of thermodynamic efiiciency, thequantity of cooling airwhich quantity may be controlled by the properchoice of the spring 45-mixed with the exhaust gases at the exhaustopening 57 is such that the temperature of the mixture exhausted throughthe opening 51 is not lowered to the most desirable value for use in theturbine 5|, rather, the temperature of this mixture is decreased furtheron mixing with the air exhausted from the compression zone 38 throughthe conduit 63.

Upon entering the discharge conduit 63, the compressed air is sprayedwith the fluid issuing from the nozzle 68, thereby reducing thetemperature of the air such that, as it passes around the tubes of thetube nest 64 in the heat exchanger 39, good heat transfer is eifectedbetween said air and the heating medium in the exchanger. This air thenpasses out of the heat exchanger through the conduit 65 into the exhaustgas flowing from the explosion chamber 36 to intermingle therewith andreduce the temperature of such gas to a degree suitable for use in theturbine 2!. After this mixture is expanded through the turbine, it isconveyed by the conduit 55 to the heat exchanger 39 Where it passesthrough the tubes of the tube nest 64, giving up a portion of its heatto the compressed air flowing around the tubes, and subsequently isdischarged through the pipe 61.

Ihe exhaust gases pass from the middle of the explosion chamber atpractically a constant pressure. This is due to the facts that theoriginal pressure wave and its reflected waves move simultaneously inopposite directions in the chamber and the reflected wave originates atthe instant the original wave has moved one half wave length. Wavesmoving in this manner will have the effect of neutralizing each other ata distance of one quarter wave length from the points of origin andreflection, in this case, at the midportion of the explosion chamber 36.

From the foregoing it will be apparent that high thermal efficienciesmay be attained in this unit by compressing the cooling air with thepressure wave in the explosion chamber and by reheating said air withthe hot gases discharged from the turbine 2 I.

It will further be apparent to those skilled in the art thatmodifications and changes may be made without departing from the spiritof the invention or the scope of the claims.

I claim:

1. A resonant explosion power unit, comprising a casing having anexplosion chamber whose length approximates an odd multiple of one halfof an explosion wave length, means for introducing the air and fuelconstituents of an explosive mixture into one end portion of theexplosion chamber, means at said end portion for igniting the explosivemixture, an exhaust conduit for conveying the explosion gases from theexplosion chamber, a valve at the other end portion of the explosionchamber acting responsively to a pressure wave of the explosion in thechamber for enabling a fluid to pass into the chamber, a conduit forconveying such fluid from the last. said portion of the explosionchamber to the exhaust conduit for cooling the hot gases therein, andmeans in the last said conduit for controlling the flow of fluidtherethrough.

2. A resonant explosion power unit, comprising a casing, an explosionchamber in the casing whose length approximates an odd multiple of onehalf wave length and having an explosion zone and a compression zone,and means for introducing the air and fuel constituents of an explosivemixture into the explosion zone, means for igniting the explosivemixture, an exhaust conduit for conveying the explosion gases from anintermediate portion of the explosion chamber, a valve actingresponsively to the pressure wave in the chamber for admitting chargesof air into the compression zone for compression by the pressure wave inthe chamber, a valve for valving the charges of air to be dischargedfrom the compression zone at a predetermined pressure, a conduit forconveying the compressed air from the compression zone to the exhaustconduit, a heater in the last mentioned means for heating the compressedair passing therethrough, and a spray nozzle in the said last mentionedmeans upstream of said heater for introducing a cooling fluid into thecompressed air flowing to the heater.

3. A gas turbine plant comprising a turbine, a compressor driven by theturbine, a casing having an explosion chamber whose length approximatesan odd multiple of one half of an explosion wave length, an explosionzone in the explosion chamber adjacent one end thereof, a compressionzone at the other end of the explosion chamber in which a supply of airis compressed by the explosion Wave, means for conveying air from thecompressor to the explosion zones, means for introducing fuel into theexplosion zone to form an explosive mixture therein, means at theexplosion zone for igniting the explosive mixture, an exhaust conduitfor conveying the explosion gases to the turbine, means for conveyingair from the compressor to the compression zone, valve means in thecasing acting responsively to a pressure wave in the chamber forallowing air to enter the compression zone and to be discharged afterbeing compressed by the explosion wave in the chamber, means forconveying air compressed by said wave from the compression chamber, aheat exchanger in the last mentioned means for heating the compressedair, and a conduit for conveying the expanded gases from the turbine tothe heat exchanger.

4. A gas turbine plant comprising a turbine, a compressor driven by theturbine, a casing having an explosion chamber whose length approximatesone half of an explosion wave length, an explosion zone in the explosionchamber adjacent one end thereof, a compression zone in the explosionchamber in which a supply of air is compressed by the explosion wave,means for conveying air from the compressor to the explosion zone, meansfor introducing fuel into the explosion zone to form an explosivemixture therein, means at the explosion zone for igniting the explosivemixture, an exhaust conduit for conveying the explosion gases to theturbine, means for conveying air from the compressor to the compressionzone, valve means in the casing acting responsively to a pressure waveinthe chamber for enabling air to enter the compression zone and to bedischarged after being compressed by the explosion wave in the chamber.a conduit for conveying the compressed air from the compression zone tothe exhaust conduit for intermingling with and cooling the explosiongases passing into the turbine, a heat exchanger in the last mentionedconduit, and a conduit for conveying the expanded gases from the turbineto the heat exchanger for heating the air flowing through the exchanger.

JAMES H. ANDERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number Number UNITED STATES PATENTS Name Date Meininghaus May 25, 1937Lysholm Apr. 26, 1938 Lysholm June 3, 1941 Ray July 18, 1944 Bodine Aug.30, 1949 Kollsman Sept. 26, 1950 Bodine Apr. 3, 1951 FOREIGN PATENTSCountry Date Great Britain Dec. 16, 1907 Great Britain Dec. 1, 1933Great Britain May 3, 1938 France May 10, 1910

